The Fairfax County school administration proposed yesterday that students begin paying up to $30 a year next fall to rent textbooks that the school system has provided free.

If approved by the county's School Board, the Fairfax system would be only the second in the region to reinstitute the so-called "textbook rentals" as a way of coping with the sharply rising costs of public education. At present, only Prince William County charges students for use of textbooks that the system has purchased with taxpayer funds.

But Fairfax School Superintendent Linton Deck said yesterday that the rental fees, designed to raise $2.75 million a year, are essential if the county is to meet his proposed $395 million school budget for the next fiscal year without digging deeper into the county's general fund, an action that could force an increase in property taxes. Members of the county board, alarmed by the size of the current year's school budget, have urged the school board to take a conservative approach in making their next budget.

Deck's proposal for textbook rentals, however, is certain to make the proposed 1982 budget one of the most controversial the school system -- now the largest in the Washington area -- has ever offered, School Board members and county officials said yesterday. Under the proposal, every elementary school student would be charged $22 a year for school books, intermediate grade students $25, and high school students, $30, the maximum.

School Board member Gerald Fill, who represents the county's Mount Vernon region, which includes a stretch of low-income homes along U.S. Rte. 1, called the proposal "a slap in the face" of the county's poor families. "They're already paying taxes" for the books, he said.

Others, including School Board Chairman Ann P. Kahn and County Board Chairman John F. Herrity, said the proposal would be given serious consideration, unlike in 1963 when the supervisors quashed a textbook rental plan after only one year. "I've always been very reluctant, personally, to invoke a textbook rental fee," said Kahn. "But I certainly will look at the proposal."

Herrity he would anticipate "a big public outcry -- both pro and con" over the proposal and said Deck "deserves a fair hearing" on the issue. He refused to take a stand on the issue, saying he would await public hearings on the proposed budget, the first that Deck has prepared since becoming head of the county schools a year ago.

Some School Board members said yesterday they were already behind the proposal. "I've been in favor of this for a long time," said Eltse Carter, School Board member form the Annandale District. "People need to have a high regard for printed matter . . . it's really just a users' fee."

Textbook rentals, while relatively rare nationally, are widespread in Virginia nationally, are widespread in Virginia, where an estimated 109 of 140 school districts charge students a fee for textbooks. Recent court challenges to the Prince William County fee system have failed to overturn the provision in the state code that allows local school boards to rent textbooks to students.

Under state law, the localities are required to provide free books to families who can't afford the rentals, but efforts to mandate free textbooks for all school children have been rejected by the conservative Virginia General Assembly.

The $395 million school budget Deck said needs to be supported by the rental fees calls for a $44 million, or 12.7 percent, increase in Fairfax school spending over the current levels. Deck, who has been outspoken on the need for the school system to modernize its technology and management techniques, called his proposal part of a "multiyear program to play catch-up" with costs that the system has deferred in recent years.

Personnel costs, including a 9.1 percent salary increase for county teachers, makes up 84.6 percent of Deck's proposed school budget. "This puts the increases where I believe they ought to be -- in the pockets of school employes," Deck said.

Deck said the school system is plagued with the perennial problem of implementing costly state and federal regulations at a time when government aid to schools appears to be ebbing."There is continuing evidence of increasing mandates with the costs to be borne by local jurisdictions," said Deck.

To cover anticipated cuts in federal aid that Deck said he expects the Reagan administration to make, the superintendent called for a $8.2 million reserve fund.

Despite a projected decline of 1,635 students during the 1982 school year, Deck's plan calls for 215 new school jobs. Included among the new hires would be 107 teacher aides and 22 people who would work in elementary schools an counselors.